1. Field of the Invention
The present invention relates to an image recording apparatus for recording images on microfilm by laser beam. More specifically, the present invention relates to an image recording apparatus for recording images on microfilm by a laser beam emitted from a laser element in an image exposure portion positioned in the film transport path wherein the microfilm is extracted from a film receptacle, transported through a film transport path and wrapped onto a film reel.
2. Description of the Related Art
In recent years a variety of devices have been proposed to record images frame-by-frame on microfilm by laser beam using roll-type microfilm. These devices comprise a cartridge for supplying raw unexposed film, a laser optical unit, a reel cartridge for winding exposed film, a film transport system for supplying raw unexposed film from the film supply cartridge to the optical unit exposure position, and a control system. The film used in the image recording device may be any commercially manufactured brand. Various films differ greatly in sensitivity characteristics depending on the manufacturer, and when jointly using films by different manufacturers the laser beam output intensity must be coordinated with the maximum exposure conditions of each film. Furthermore, even when using film by the same manufacturer, the finish density may be optionally varied according to the needs of the principle user. Therefore, it is desirable to provide a control knob on the operation panel of the image recording device to allow modulation of the laser beam output intensity.
Methods for modulating laser output include well-known methods of controlling monitoring current. However, the circuit carrying the monitoring current is readily affected by external noise because it is an analog circuit. A portion of the circuit carrying the monitoring current is a direct long lead line connected to the operation panel of the device and may produce faulty operation by the operation panel due to the aforesaid noise influence, such that in a worst case instance of said noise influence excessive current may flow to the laser element causing the laser element itself to be damaged.